Overview
Hsu and colleagues simmered pig and cow bones under controlled conditions (acidity, bone type, species, up to 12 hours) and also analyzed the broth from three kinds of commercial bone-broth street foods in central Taiwan. Lead and cadmium in commercial broths were a few µg/kg, giving a few micrograms per serving at most. Acidifying the broth raised calcium and magnesium extraction about 15 to 17 times, but broths still supplied under 5 percent of daily needs.
Key numbers
- Lead in commercial broth: mean 2.63 ppb (herbal pork rib, n=7), 3.64 ppb (beef noodle soup, n=6, max 9.39), 4.27 ppb (pork-bone ramen, n=6) (Table 2).
- Cadmium: mean 0.27-0.64 ppb, max 1.68 ppb (Table 2).
- Aluminum: mean 0.49-0.78 ppm, max 3.16 ppm in pork-bone ramen broth (Table 2).
- Lab broths: lead extracted 2.53-9.01 µg per kg of bone with no significant change over 12 hours of simmering (Table 1).
Methods (brief)
Filtered broth (100 mL) was digested with hydrochloric and nitric acids on a hot plate. Lead, cadmium, copper and chromium were measured by ICP-MS (detection limits 0.17-0.27 ppb) and the major elements by ICP-OES. Spike recoveries were 86 to 110 percent; calibration used certified standards, with no food reference material.
Evidence Fitness
Good analytical sensitivity for lead and cadmium, but small commercial samples from one city with no collection dates. Cadmium means sit close to the detection limit. The experimental results are metal mass per kg of bone, not broth concentrations. No chicken broth was tested, so this is a proxy for chicken-broth, chicken-noodle-soup, vegetable-beef-soup and brown-gravy. The ramen broth is a fresh pork-bone noodle-soup broth, not instant ramen, and is only a proxy for ramen-soup. None of these pages is linked.